Due how many weeks

Use this calculator by plugging in either the date of your last menstrual cycle or the date of conception. That's it! The pregnancy calculator will do the rest! There are several ways. If you happen to know the day you conceived, you can count 38 weeks from that day to find your due date.

Human gestation takes about 38 weeks. But very few expectant moms know exactly when they conceived. Even if you only had sex once during your fertile period , you wouldn't conceive on that day unless you happen to be ovulating. Sperm can live for up to five days inside your fallopian tubes. So, it could be up to five days after you have sex that you release an egg ovulate and it gets fertilized by a waiting sperm.

That's the day you conceive. The most common way to calculate your pregnancy due date is by counting 40 weeks from the first day of your last menstrual period LMP. And that's how most healthcare providers do it. If your menstrual cycle length is the average length day cycle , your menstrual cycle probably started about two weeks before you conceived. This explains why pregnancies are said to last 40 weeks instead of 38 weeks.

This method doesn't take into account how long your menstrual cycle actually is or when you think you might have conceived. But generally speaking, women typically ovulate about two weeks after their menstrual cycle starts. And women are more likely to know when their last period started than the day they ovulated. If you do happen to know precisely when you conceived — say, if you were using an ovulation predictor kit or tracking your ovulation symptoms — you can calculate your pregnancy due date based on your conception date.

Just choose that calculation method from the pulldown above and put in your date. Note: Again, you don't necessarily conceive on the day you have sex. But for a fun read, see our stories from parents who know when and where they did the deed that resulted in their child. Using both the date of your last period and the length of your regular cycle, or exact date of conception, our due date calculator will quickly work out your estimated due date, tailoring it accordingly for longer, shorter, and average cycle lengths.

At each following prenatal care appointment, you'll be examined to determine the size of your uterus, and to monitor your little one's development.

Along the way, depending on what is observed, your pregnancy due date may be adjusted. Explore the rest of our site to find out more. Choose your method:. This period is known as gestational aging. If you require more options to calcuate your due date or how far along you are, try our due date calulator. Pregnancy is estimated to be 40 weeks or days from the first day of a woman's last menstrual period LMP.

The actual length of pregnancy varies significantly among women. If you don't have a valid last menstrual period date for any reason, your doctor will provide one for you, most likely based on ultrasound measurements. Generally, obstetricians or physicians initially calculate pregnancy from your last period without adjusting for an irregular cycle length. This initial estimation may then be superseded or confirmed by an ultrasound. Read more about ultrasound on this page or our due date page.

Pregnancy is counted from a women's last menstrual period because the start of a period is easily observable and usually known to a woman whereas the date of conception is much less likely to be known.

Historically, the first day of the last menstrual period LMP became the date from which pregnancy is counted even though conception occurs about two weeks later. The LMP formula is good for working out an initial age of pregnancy but ultrasound is more accurate. Ultrasound in the first trimester is the most accurate method of dating pregnancy.